Carburetor



Dec. 18, 1928.

H. C. TILLOTSON ET AL CARBURETOR Filed March 31. 1922 M "l ill A 1| 1 4 I 44 1I a i P "l l z5? XE I 3;

/Zp /o z/ 7 AO 8 53 ATTORNEY Patented Dec. 1.8, 1928.

UNITED STATES PATENT OFFICE.

HARRY C. TILLOTSON, EARL A. RULLISON, AND CHARLES W. MCKINLEY, OF TOLEDO, OHIO, ASSIGNORS T THE TILLOTSON MANUFACTURING CO., 0F TOLEDO, OHIO, A

CORPORATION OF OHIO.

. CARBURETOR.

Application led March 31, 1922. Serial No. 548,271.

This inventionrelates to improvements in carburetors, having reference particularly to the fuel supply for idling.

In carburetor practice, it is quite customhary to provide an idling nozzle for supplying fuel to the engine when the throttle valve is closed or nearly closed, or in idling position, at which time the main nozzle is ineffective. In carburetors of this character the vacuum affecting the idling nozzle decreases very rapidly as the throttle is opened. This reduces the flow of mixture to the idling nozzle and coupled with the excess of air admitted by the throttle produces ay mixture too lean to give satisfactory results. Until the engine attains a cert-ain speed, equivalent to from six to ten miles an hour vehicle speed for certain motor vehicles, the suction is insufficient to draw a charge from the main nozzle around which the vacuum is not very great because the flow of air around the nozzle necessarily is not much restricted. At

such engine speeds, therefore, the engine will fail to run satisfactorily, this phenomenon being called frequently a spot One of the objects of this inventlon is the provision of means to eliminate such spots Another difliculty often met with is the failure of the carburetor to provide a sulficiently rich fuel mixture at times when it is desired to apply a load to the engine more or less suddenly, as when the s eed of the -vehicle is to be accelerated. uxiliary wells in which a reserve of fuel is collected to be drawn upon onlySduring acceleration of the engine have been frequently utilized for the purpose of overcoming this ditliculty. An.- other object of this invention is the provision of a means of this character which is so arranged and constituted that at high' engine.

speed the richness of the mixture is autol matically vreduced or at any rate not increased, thus effecting economy in operation at hi h speed.

Ot e'r objects of the invention relating to details of construction and economies of manufacture will ap ear as we proceed with the description of t at embodiment of the invention which for the purposes of the pres ent application We have illustrated in the accompanying drawing'v in which:

Figure I is a vertical section taken throughV the middle ofthe nozzle and carbureting chamber and throughv the oat bowl.

Similar reference characters refer to like parts throughout the views.

In the drawing, the numeral indicates the casing of the carburetor proper while- 11 is the float bowl having a cover l2. In the casing 10 there is a horizontal air inlet portion 13 controlled by a choke valve 14C and a vertical mixing chamber 15 containing the usualventuri 16 and throttle valve 17. The attaching flange 18 may be integral with the upper portion of the casing.

A nozzle device arranged axially of the mixing chamber is formed preferably of three concentric spaced tubes 19, and 21. From an inspection of Fig. III in particular, it will noted that the inner tube 19 is spaced uniformly from the intermediate tube 20. Intermediate tube 20 however, includes an enlarged middle portion 22 running en`- tirely around the periphery whereby there are formed in eect three different cylindrical spaces between t-he intermediate and outer tubes 20 and 21 respectively. The middle cylindrical space is extremely narrow. A measurement of about one-one hundredth inch on each side has been found to be satisfactory. This space is too minute to be shown on the small scale of Fig. I.

The lower cylindrical space between` the tubes 20 and 21 is connected with the space between the tubes 19 and 20 by af ort 23 through the' tube 20. The upper en of the ing the operation of the carburetor. Another Series of ports 25 through the inner tube 19 I v are located at some little distance above the normal fuel level.. The outer tube 21 is provided with a series of eight in number, locate thus producing a series of fuel sprays around. the periphery of the nozzle in order to assist ip breaking up the mixture into fine parti c es.

orts 26, preferably above the `ports 24 ion The manner of mounting the three tubes 19, l

20 and 21 may be varied so long as means 'are provided for properly centering the tubes and for sealing the lower extremities of the intermediate and outer tubes. The means illustrated in the drawing is satisfactoryfrom a manufacturing as well as from-an operative standpoint. In the structure shown the outer tube 21 is provided with a peripheral collar 27 adapted to fit closely within the smooth linner portion of an openingr 28 extending upwardly from the bottom of the casing 10.

When the parts are assembled, this collar 27 bears against a packing ring 29 which rests in turn. against an annular shoulder overhanging the opening 28. The outer tube is forced into position and held there by engagement at its lower extremity with a flange 30 on the end of the intermediate tube 20. This flange is conical on its lower side for engagement with a conical surface on an externally threaded nut 31. In this manner assembly of the tubes is much facilitated, since the middle tube is centered and the middle and outer tubes forced into position and held there by the tightening ofthe single nut 31.

The nut 31 is provided with a central orifice of suilicient size to accommodate the tube 19 and to provide a cylindrical passage around 1he exterior thereof. The tube 19 is tightly mounted at its lower end in a nut 32 whereby it is centered and held in position. The upper ends of the tubes are fitted tightly one into the other.

rIhe main fuel passage of the carburetor comprises a short vertical bore 33 leading downwardly from the float bowl into a bore 34 of larger diameter. A calibrated plug 35 connects these two bores. Plugs 35 having diferent sized openings therethrough may of course be employed interchangeably, or other nieans for accomplishing the same end, such for instance, as an adjustable valve; may be substituted if desired.` A. horizontal bore 36 connects the vertical bore 34 with a space 37 between the nuts 31 and 32, the bore 36 being interrupted intermediate its length by a vert-ical screw threaded bore 38.

Just above the bottomfof the tube 21 there are relatively large openings 39 communicating with a peripheral passage around the exterior of the tube 20, which in turn communicates with an auxiliary fuel well consisting of the horizontal portion 40 and vthe vertical portion 41, the latter being a bore concentric with the bore 38 and openingthereinto. The two bores 38 and 41 are. connected by a calibrated plug 42 which is provided on its upper side with a conical surface adapted to center and form a tight joint with the lower end of a by-pass tube 43 which protrudes through `the casing at the upper end of the bore 41 and connects with a small chamber or passageway 44 having an air inlet 45 arranged to i be opened to a greater or lesser extent by a conical or needle valve 46 threaded into the casing and provided with a thumb piece 47. The chamber 44 is connected `with the mixing chamber 15 by means of two vertically spaced ports or outlets 48 and 49 the upper one of which is always open and the lower one of which is vopen only when the throttle shutter 17 is open more or less. The upper end of the auxiliary fuel well 40 and 41 above the fuel level has constricted communication with the atmosphere through a calibrated plug 50. The parts 51, 52, 53, 54 and are merely threaded plugs for closing' the ends of the bores into which they are tted.

Operation.

When an engine to which this carburetor is attached is idling, fuel passes from the float bowl through bore 33, calibrated plug 35, bores 34, 36 and 38, calibrated plug 42, by-pass tube 43, chamber 44 and port 48 into the mixing chamber 15, and thence into the engine manifold, the fuel when it reaches the chainber 44 being mixed with air coming through the passage 45. It is characteristic of this arrangement for supplying the fuel mixture for idling purposes that the liquid fuel is drawn from a point beneath the normal level of the fuel in the float bowl and free from adinixture with air prior to its delivery to the chamber or passageway 44. The delivery of fuel to chamber 44 and its mixture with air at that point. is, of course, dependent upon the engine demand through the port- 48 alone or in conjunction with 49 as the position of the throttle 17 over the latter may permit. As the throttle. 17 is opened slightly, port 49 as shown is also immediately or progressively Sii uncovered, whereupon a larger quantity of i mixture is led into the manifold. This quantity of-explosive mixture is sufficient to insure satisfactory operation of the engine until Fuel for the main nozzle is delivered through the passages 33, 34 and 36 into the space 37 and then upwardly between the tube 19 and the nut 3l into the cylindrical space between tubes 19 and 20, passing upwardly as far as ports 24. Here it meets a downwardly moving cylindrical column of air coming from the open lower end of the tube 19 upwardly through that tube and through the ports 25 at the upper end thereof. This provision for causing a downward flow of air to meet an upward flow of fuel results in the air holding back the flow of fuel so that instead of the usual increase in the proportion of fuel to air ratio as engine speed increases, a constant or diminishing ratiois maintained as inoie air is drawn through the venturi.

Air and fuel pass together through the ports 24 being thereby commingled to a greater or lesser extent. This mixture is then caused by engine suction to move upwardly into the cylindrical space between the upper portion of tubes 20 and 21 and then out through the numerous holes 26, thereby being broken up into a fine vapor which mingles intimately with the air passing rapidly through the venturi surrounding the nozzle.

At the same time that the suction of the engine causes the flow of gas justdescribed, suction becomes effective through the ports 26 and the restricted cylindrical passage between the two outer tubes 20 and 21 to reduce the pressule in the auxiliary lwell 40, 41. While this Well is in communication with the atmosphere through the restricted opening in the calibrated plug the latter opening is not large enough to maintain atmospheric pressure in the well when the latter is subjected to the suction effect referred to. The low pressure in this well assisted by gravity causes fuel to flow through the port 23 in the intermediate tube 20 and through openings 39 into the well. The relative amount of suction effective to lift fuel into the auxiliary well is dependent upon the amount of clearf ance between the tubes 20 and 21 and upon the size of the hole in the plug 50.

At any given engine speed, if-the throttle of a carburetor is suddenly closed or nearly closed, vthe vacuum lin the manifold is in-- creased above the vaporization point of the fuel and all the liquid inthemanifold is vaporized. Unfortunately the reverse is also true, that is, if the throttle is suddenly opened, liquid is thown out of the mixture in the manifold and wets the walls of the latter, resulting in an impoverishment of the mixture. To make up this impoverishment it is necessary t' supply a temporarily rich mixture during acceleration. This is accomplished in the present instance by drawing upon the supply of fuel in the auxiliary `wells 40, 41. When the throttle is opened suddenly, ,producing an increased suction effect upon the nozzle, the fuel begins to flow out ot' the auxiliary well to the upper end of the nozzle, up between the two outer tubes, also possibly directly through the hole 23 and up between the two inner tubes.

()ur apparatus is designed as to the restricted space between the two o uter tubes 20 and 21 and as to the size of the opening in calibrated plug 50, so that when a certain redetermned speed is reached and excee ed, the low of fuel through the'port 23 and openings 39 into the auxiliary well is not only reversed, but the supply of fuel in the auxiliary well is exhausted to such an extent that air begins to flow through the plug 50v and auxiliary well up through the Ort- 23, and also through-the restricted space etween thc two outer tubes 20 and 21, thus tending to reduce still further the richness of the mixture at high engine speeds.

ln a few words, therefore, certain import ant features of our invention consist in means for obtaining the result that when a small volume of air passes through the venturi, the auxiliary well fills to a certain level with fuel, and upon sudden opening of the throttle, this fuel is drawn out of the auxiliary'well to supply the necessary enrichment of the mixture, while thereafter, if a comparatively high speed is maintained, air is bled through the plug 50 and auxiliary well, giving a highly desirable thinning-out effect.

l-Vhile we have described more or less in detail a specific embodiment of our invention, it is to be understood that the foregoingshowing and description are illustrative only and for the purpose of making the disclosure of the invention thoroughly clear and understandable. We do not regard the invention as limited to the details of construction illustrat-ed or described herein, except in so far as we have included such limitations within the terms of the 'following claims, in which it is our intention to' claim all novelty inherent in the invention broadly as Well as specifically.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. In a carburetor; a. main nozzle; a mixing chamber; a throttle valve therein; a fuel supply for said nozzle; 'a liquid f uel by-pass from said fuel supply; means for admitting a calibrated quantity of air to said by-pass; a port from said ley-pass above said throttle valve in the idling position of the latter,` and a second port from said by-,p'ass into-said mixing chamber substantially closed by said throttle valve against intake into said bypass in said idling position but beyond said throttle when the latter is opened slightly whereby an additional quantity of mixture from said by-pass is admitted to said mixing chamber.

2. A carburetor having a main nozzle; a fuel supply for said nozzle; a main mixing chamber; means for throttling mixture flow to the engine; an auxiliary mixing passageway; a separate auxiliary liquid fuel delivery means from said fuel supp-ly for'said auxiliary mixing passageway; means for admitting air to said auxiliary liquid fuel; outlet means from said auxiliary passageway arranged to discharge into said mixing chamber when said throttle is in idling posit-ion; and additional outlet means from said auxiliary passageway, said latter means being substantially closedagainst intake therethrough,

by said throttling means in said idling position, but opened to discharge from said auxiliary passageway when said throttle is opened from said idling position.

. 3. A carburetor having a main nozzle; a fuel supply for said nozzle; a-main mixing chamber; means for throttling mixture flow to the engine; an auxiliary mixing passageway; an auxiliary liquid fuel orifice connectl10- discharge into said mixing chamber whensaid t-hrottling means is in idling position; and additional outlet means from said auxiliary passageway7 said latter means being rendered inactive tov discharge of mixture into said main mixing chamber when said throttling means is in said idling position, but rendered active to discharge froinsaid auxiliary passageway when said throttle is opened from said idling position; and common means for adjusting said auxiliary air supply for regulating the mixture rat-io issuing from both outlet means.

4. A carburetor having a main nozzle; a fuel supply for said nozzle: a. main mixing chamber; means for throttling mixture iow to the engine; an auxiliary mixing passage- Way; an auxiliary liquid fuel delivery means y from said fuel supply for said auxiliary mixing passageway; means for admitting air to said auxiliary liquid fuel; means for admittingy air into said main nozzle; outlet means from said auxiliary passageway arranged to discharge into said mixing chamber when saidthrot-tle is in idling posit-ion; and additional outlet means from said auxiliary passageway; said latter means bein substantially closed against intake tlieret rough by said throttling means in said idling position but opened to discharge from said auxiliary passageway when said throttle is opened from vsaid idling position.

In testimony whereof, we aix our signatures.

HARRY c. TiLLoTsoN. EARL A. RULLisoN. CHARLES W. MGKINLEY. 

